How to Calculate Percentage of a Number ?

Calculating percentages is one of the most practical math skills you can learn. From determining discounts during shopping to calculating interest rates or exam results, understanding how to work with percentages is essential in everyday life, business, and finance.

This guide explains, in simple terms, how to calculate percentages using different methods — with examples to help you master the concept easily.

What Is a Percentage?

A percentage is a way of expressing a number as a fraction of 100. It is represented by the percent symbol (%) and helps compare quantities or express proportions.

For example:

• 50% means 50 out of 100, or half of the whole.

• 25% means 25 out of 100, or a quarter of the whole.

Basic Formula to Calculate a Percentage

The standard formula to find the percentage of any value is:

Percentage = (Part ÷ Total) × 100

This formula helps determine what portion one value represents out of another.

How to Find a Percentage of a Number

To calculate a specific percentage of a number, use this formula:

Result = (Percentage ÷ 100) × Total Number

Example 1: Find 20% of 150
(20 ÷ 100) × 150 = 0.2 × 150 = 30

✅ Answer: 20% of 150 is 30

How to Convert a Fraction or Decimal into a Percentage

You can easily convert fractions or decimals into percentages using these simple methods:

• For Fractions: Divide the numerator by the denominator, then multiply by 100.

• For Decimals: Multiply the decimal by 100 and add the percent sign (%).

Example 2: Convert 0.75 to a percentage
0.75 × 100 = 75%

✅ Answer: 0.75 equals 75%

How to Find What Percentage One Number Is of Another

To determine what percentage one number represents of another, use this formula:

Percentage = (Part ÷ Whole) × 100

Example 3: What percentage is 30 of 200?
(30 ÷ 200) × 100 = 15%

✅ Answer: 30 is 15% of 200.

How to Increase or Decrease a Number by a Percentage

1. Increasing a Number by a Percentage

New Value = Original Value + (Percentage ÷ 100 × Original Value)

Example 4: Increase 500 by 10%
500 + (10 ÷ 100 × 500) = 500 + 50 = 550

✅ Answer: 500 increased by 10% equals 550.

2. Decreasing a Number by a Percentage

New Value = Original Value − (Percentage ÷ 100 × Original Value)

Example 5: Decrease 600 by 25%
600 − (25 ÷ 100 × 600) = 600 − 150 = 450

Answer: 600 decreased by 25% equals 450.

Real-World Applications of Percentages

Percentages are everywhere in daily life. Here are some common examples:

• 🛍️ Shopping Discounts: Calculate sale prices after applying discounts.

• 💰 Taxes & Tips: Figure out sales tax or restaurant tips.

• 🏦 Finance & Interest Rates: Understand how savings and loans grow over time.

• 🎓 Exam Scores: Schools often grade students using percentage scores.

Common Mistakes to Avoid

When calculating percentages, watch out for these common errors:

•  Forgetting to divide by 100 when converting to a percentage.

•  Misplacing decimal points.

•  Mixing up percentage increase and decrease formulas.

Calculating percentages is a fundamental math skill that simplifies financial planning, shopping, academic grading, and data analysis.
By practicing these formulas and understanding their logic, you’ll find that percentage calculations become quick, easy, and reliable — a skill that pays off in every area of life.